#include "my_stdio.h"
#include<stdlib.h>
#include<sys/types.h>
#include<sys/stat.h>
#include<fcntl.h>
#include<string.h>
#include<unistd.h>
mFILE *mfopen(const char *filename,const char *mode)
{
    int fd = -1;
    if(strcmp(mode,"r") == 0)
    {
	fd = open(filename,O_RDONLY);
    }
    else if(strcmp(mode,"w") == 0)
    {
	fd = open(filename,O_CREAT | O_TRUNC | O_WRONLY, 0666);
    }
    else if(strcmp(mode,"a") == 0)
    {
	fd = open(filename,O_CREAT | O_WRONLY | O_APPEND, 0666);
    }

    if(fd < 0)
	return NULL;
    mFILE *mf = (mFILE*)malloc(sizeof(mFILE));
    if(!mf)
    {
	close(fd);
	return NULL;
    }
    mf->fileno = fd;
    mf->flag = FLUSH_LINE;
    mf->cap = SIZE;
    mf->size = 0;
    return mf;

}


void mfflush(mFILE *stream)
{
    if(stream->size > 0)
    {
	//写到文件的内核级缓冲区中
	write(stream->fileno, stream->outbuffer, stream->size);
	//刷新到外设
	fsync(stream->fileno);
	stream->size = 0;
    }
}
int mfwrite(const void *ptr, int num, mFILE *stream)
{
    // 1.拷贝
    //没有考虑溢出
    memcpy(stream->outbuffer+stream->size, ptr, num);
    stream->size += num;

    // 2.检测是否要刷新
    if(stream->flag == FLUSH_LINE && stream->size > 0 && stream->outbuffer[stream->size-1] == '\n')
    {
	mfflush(stream);
    }
    if(stream->flag == FLUSH_FULL && stream->cap == stream->size)
    {
	mfflush(stream);
    }
    return num;
}

void mfclose(mFILE *stream)
{
    if(stream->size > 0)
    {
	mfflush(stream);
    }
    close(stream->fileno);
   
}
